SAS, Thanks, but you perhaps forget others here also have considerable experience of helicopter instrument approaches in all sorts of circumstances - there are even some of us with relevant type ratings and a lot of hours on the type...in my case as many as you previously said you flew on the Chinook. I had already worked out that one needs to fly with consideration of the prevailing conditions, but thanks for the reminder.
I have no reason to ask JD to corroborate your story about the speed at which you flew that ILS at WPB; I believe you, it's not unique (I have been in a situation in an A109S where, having been directed by ATC at a major airport to "make best speed" on the ILS to fit in with the busy airliner traffic I was shortly afterwards asked to slow down again because I was catching up the B767 established ahead of me).
Are you saying that you usually changed the IAS on a S-76 on a coupled ILS by manually lowering the lever, or did you use the "Beep" trim with IAS mode selected, as per normal teaching and allow the AP to reduce the power accordingly? I did the latter, as I was taught to do and expected to do for the nine year period I flew them (A, A++, B, C and C+).
Did you keep your feet on the side rests on the yaw pedals and away from the yaw micro-switches so the AP could make it's own yaw inputs? I certainly did.
Unfortunately, you don't have that luxury of doing either in the A109S - the aircraft has no IAS mode when coupled on the ILS and the AP requires the pilot to make all yaw pedal inputs himself and to re-trim them, the trim release button on the
cyclic has to be used. In effect, the A109S cannot be flown "fully coupled" on an ILS, unlike more sophisticated aircraft.
When it comes to a speed reduction near the ground, the normal teaching (at least the teaching I am familiar with) is to initiate the manoeuvre by using the cyclic to raise the nose to a decelerative attitude then to maintain the required flight path by lowering the collective. In the A109S, if still coupled at the bottom of an ILS and the system has levelled the aircraft at 50 feet (as advertised), to reduce speed the pilot has to first lower the collective and trust that the AP will prevent a descent by raising the nose. If you try to move the cyclic first you will find yourself working against the trim - not something you should be doing near the ground in poor visibility. The more sophisticated types such as the S-76 (and. I believe, the A109SP) will slow down all by itself in the same circumstances because the collective is also coupled).
It's unlikely we will ever know what this unfortunate pilot did because there is no FDR on the type. I would be interested to find out what his previous experience was.